Process for treating mineral oils



Patented Sept. 10, 1940 UNITED STATES PATENT OFFICE N Drawing.

Application March 2, 1937,

Serial No. 128,618

8 Claims.

This invention pertains generally to the improvement of oils and pertains particularly to the stabilization thereof.

This invention pertains more particularly to the stabilization of lubricating oils intended for motor car use.

The result of improvements in the automobile motor to develop more power at higher operating temperatures with units occupying smaller space, has been to place a much greater demand upon motor oils.

While commercial motor oils as a rule and particularly those made from Pennsylvania grade crudes are composed of highly inert substances capable of heavy duty performance without substantial change in chemical composition, yet extreme service conditions'particularIy when accompanied by high temperatures, are sometimes capable of causing undesirable chemical and/or physical changes as evidenced, for instance, by the corrosion of certain types of bearings.

This invention is based upon the discovery that the stability of oils in general, and particularly those derived from Pennsylvania grade crudes is materially. improved upon the addition to said oil of a relatively small amount of a new stabilizing substance made by treating a phenol and particularly a simple phenol such as carbolic acid with arsenious chloride, preferably in stoichiometric proportions such as would be required for instance in making triphenyl arsenite.

The following will illustrate the manufacture of this new stabilizing substance.

To 3 mole of phenol (carbolic acid) is added 1 mole of arsenious chloride, preferably with a slight addition of heat, say for instance sufficient to cause the reaction to take place at 50 C. The reaction which takes place is accompanied by the evolution of a gaseous substance which is After the reaction is complete the dissolved gas is preferably removed by any suitable means known in the art.

In case phenol is used as a starting material the resulting molecule is thought to contain three benzene rings, each linked to a single arsenic atom by means of an oxygen atom and will be hereinafter referred to as triphenyl arsenite.

In case cresol is used as a starting material each of the three benzene rings is thought to contain a methyl group and the resulting substance will be hereinafter referred to as tricresyl arsem'te.

When my new stabilizing substance is added to a lubricating oil for instance to the extent of thought to be at least chiefly hydrogen chloride.

0.5 percent by weight it prevents the corrosion of certain types of bearings as shown by the following test.

150 cubic centimeters of oil to be tested is placed in a glass test tube and raised to 341 F. Bearing sections are placed in the oil on glass hooks and a strip of copper having an'area of 21 square centimeters is added to catalyze oxidation of the oil and thereby increase the severity of the test. 5 liters of air are passed through the oil per hour. At definite time intervals the bearings are removed, cleaned and weighed. The loss in weight after cleaning is taken as a measure of the degree of corrosion.

To illustrate the stabilizing qualities of my new stabiliizng substance an untreated neutral oil was subjected to the foregoing test in the presence of a cadmium-nickel alloy bearing section having an area of 21 square centimeters. At the end of 12 hours the bearing section showed a loss due to corrosion of approximately milligrams.

This same oil was treated with 0.5 percentby weight of triphenyl arsenite followed by thorough mixing and when subjected to the same test for a period of 12 hours there was no loss in weight of the cadmium-nickel bearing section due to corrosion.

The stabilizing effect of my new stabilizing substance is thus made clearly evident.

In view of the fact that the above test is extremely severe it follows that good results may be produced upon the addition of smaller quantities of the stabilizing substance. On the other hand, if desired, larger quantities may be added.

No difliculties have been experienced in bringing larger quantities of the stabilizing substance into solution in the oil. However, if desired, solubilizing agents may be added.

It is to be understood that the foregoing description of a manner of making the stabilizing substance is by way of illustration and not of limitation.

A variety of substances may be used as starting materials in the manufacture of the stabilizing substance, or other means may be employed for building up the stabilizing molecule.

Further evidence of the stabilizing effects of my new stabilizing substance appears to reside in the improvement in other lubricating qualities.

Oils treated in accordance with this invention may be used for any other purpose such as in- .sulating oils for transformers, cables, etc., or for other lubricating purposes.

In the claims the term lubricating oil when referred to is intended to mean a petroleum oil of a viscous character, that is, an oil having a viscosity of the order of Saybolt seconds at F. or more and regardless of the use to which such oil is put.

While procedure for the purpose of carrying out the invention has been particularly described it is to be understood that this is by way of illustration. Therefore changes, omissions, additions, substitutions, and/or modifications may be made within the scope of the claims without departing from the spirit of the invention which is intended to be limited only as required by the prior art.

I claim:

1. A process for stabilizing a lubricating oil comprising adding to said oil a quantity sufiicient to inhibit corrosion of a stabilizing substance resulting from attaching three phenolate groups to a single arsenic atom.

2. A process for stabilizing a lubricating oil comprising adding to said oil in quantity sufficient to inhibit corrosion triphenyl arsenite.

3. A process for stabilizing a lubricating. oil comprising adding to said oil in quantity sufii- 'cient to inhibit corrosion tricresyl arsenite.

corrode alloys having the corrosion susceptibility of cadmium-nickel alloys when continuously applied to the surface thereof under service conditions, comprising incorporating with said oil triphenyl arsenite in at least corrosion inhibiting proportions.

5. A lubricating oil having in solution therein a quantity sufficient to inhibit corrosion of a substance resulting from attaching three phenolate groups to a single arsenic atom.

6. A lubricating oil having in solution therein triphenyl arsenite in quantity sufiicient toinhibit corrosion.

7. A lubricating oil having in solution therein tricresyl arsenite in quantity suflicient to inhibit corrosion.

8. Mineral oil composition comprising a hydrocarbon lubricating oil of a character normally tending to corrode alloys having the corrosion susceptibility of cadmium-nickel alloys When continuously applied to the surface thereof under service conditions, and triphenyl arsenite incorporated with said oil in at least corrosion inhibiting proportions.

KEGHAM A. VARTERESSIAN. 

